Biotransformation of pungent constituents from ginger (Zingiber officinale Roscoe) by Colletotrichum gloeosporioides yields oxidative ortho–ortho coupling products

Abstract

This work investigated the biotransformation of ginger constituents (zingerone, [6]-shogaol, [6]-gingerol, and methyl-[6]-gingerol) by the pathogenic fungus Colletotrichum gloeosporioides. Experiments were carried out with and without deuterium-labelled compounds. The product metabolites were analyzed by liquid chromatography coupled to tandem mass spectrometry and liquid chromatography solid phase extraction-nuclear magnetic resonance. Substrates supplied to the fungus were incorporated into metabolic pathways mostly by oxidation reactions, including aromatic carbon–carbon coupling. Zingerone and [6]-gingerol biotransformation products included biphenol dimers. A biodegradation pathway for biphenol formation was proposed based on the presence of the intermediate 4-(2-hydroxyethyl)-2-methoxyphenol, commonly identified from [6]-gingerol and [6]-shogaol biodegradation. This intermediate likely originates from a Baeyer–Villiger reaction followed by hydrolysis. The C–C coupling of molecules could result in phenolic oxidative ortho–ortho coupling, suggesting that biphenol dimers are products of C. gloeosporioides laccase catalysis.

Graphical Abstract

Keywords:

• Biotransformation
• Colletotrichum gloeosporioides
• biphenol
• ginger

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The present work was financially supported by the São Paulo Research Foundation (FAPESP) (Grant # 14/50249-8) and the Coordination for the Improvement of Higher Education Personnel (CAPES, Finance Code 001).